In the article written by an American Muslim convert fighting in Syria, followers in the West are urged to carry out attacks at home if they are thwarted from travelling to the Middle East.

In the article written by an American Muslim convert fighting in Syria, followers in the West are urged to carry out attacks at home if they are thwarted from travelling to the Middle East.(AFP file photo)

The dreaded ISIS has instructed its Western terror recruits to embark upon “simple and effective” spontaneous attacks rather than making “intricate” plans in the latest edition of its online propaganda magazine.

“Indeed, you are behind enemy lines, able to strike them where it hurts them most. The command is clear. Kill the disbelievers,” the article in ‘Dabiq’ reads.

“As for a final word of advice... do not make intricate plans, but instead keep it simple and effective. If you can obtain a weapon, do so and use it as soon as possible and in a place that will cause the most damage and panic,” it adds.

In the article written by an American Muslim convert fighting in Syria, followers in the West are urged to carry out attacks at home if they are thwarted from travelling to the Middle East.

“If you are unable to do so, know that you have been blessed with the opportunity to serve a much greater purpose than dwelling among Muslims,” it says in its message to Western IS recruits.

The new instructions reported in ‘The Sunday Times’ emerge as Scotland Yard chief Sir Bernard Hogan-Howe warned recently that it was “a case of when, not if” an attack would be launched in the UK.

The force had also announced an additional 600 armed officers to guard major spots around London earlier this week.

Since August 2014, the terror threat level in Britain has been “severe” -- the second highest level -- meaning an attack is “highly likely”.